{"gene":"SAMD4B","run_date":"2026-06-10T07:46:29","timeline":{"discoveries":[{"year":2010,"finding":"SAMD4B suppresses transcriptional activity of AP-1, p53, and p21 when overexpressed in mammalian cells; deletion analysis showed the SAM domain is the primary region responsible for transcriptional suppression, and the inhibitory effects could be relieved by siRNA knockdown.","method":"Transcriptional activity (luciferase) assays, overexpression and siRNA knockdown in mammalian cells, deletion mutagenesis","journal":"BMB reports","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional assays with deletion mutagenesis and siRNA rescue in a single lab, single study","pmids":["20510020"],"is_preprint":false},{"year":2021,"finding":"SAMD4B is a direct target of miR-451; luciferase reporter assay validated miR-451 binding to the 3′-UTR of SAMD4B, and overexpression of miR-451 inhibited CRC cell proliferation and migration partly by suppressing SAMD4B expression.","method":"Dual luciferase reporter assay (3′-UTR binding), miRNA mimic/inhibitor transfection, SAMD4B plasmid overexpression, CCK-8/Transwell/flow cytometry, xenograft model","journal":"Molecular medicine reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — binding site validated by luciferase reporter plus functional rescue experiments in vitro and in vivo, single lab","pmids":["34109425"],"is_preprint":false},{"year":2025,"finding":"BAG2 directly binds SAMD4B; when arginine is abundant, BAG2–SAMD4B interaction prevents β-catenin degradation and activates the Wnt/β-catenin pathway. Upon arginine deficiency, BAG2 (acting as an arginine sensor via Q167) releases SAMD4B, leading to β-catenin degradation, ATF4 stabilization, and enhanced cell survival.","method":"Unbiased screening in cancer cell lines, direct binding assays (BAG2–arginine interaction at Q167), protein–protein interaction assays (BAG2–SAMD4B), functional pathway readouts (β-catenin levels, ATF4 stability, Wnt pathway activity)","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal methods including direct binding assays, mutagenesis of BAG2 Q167, mechanistic pathway readouts; single lab but rigorous, published in high-tier journal","pmids":["40555234"],"is_preprint":false},{"year":2025,"finding":"SAMD4B promotes breast cancer cell proliferation, migration, invasion, and EMT, and accelerates G1-to-S cell cycle progression by modulating p53 expression; mechanistically, SAMD4B stabilizes β-catenin mRNA, increases β-catenin protein, and upregulates Wnt/β-catenin target genes (Cyclin D1, c-Myc, Axin2, TCF/LEF activity). Inhibition of the pathway with XAV-939 abrogated these effects.","method":"SAMD4B overexpression/knockdown functional assays (proliferation, migration, invasion, cell cycle analysis), western blot for β-catenin and downstream targets, TCF/LEF reporter assay, β-catenin mRNA stability analysis, XAV-939 pharmacological inhibition","journal":"Biomolecules","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal functional and biochemical methods in a single lab study with pathway inhibitor validation","pmids":["41154652"],"is_preprint":false},{"year":2024,"finding":"SAMD4B mediates 2′-O-methylation modification that destabilizes APOA2 mRNA; decreased APOA2 reduces PD-L1 levels through a direct interaction, thereby modulating the tumor immune microenvironment in HCC.","method":"2′-O-methylation modification assays, multiplex immunofluorescence staining, single-cell RNA sequencing in PDX models, mechanistic pathway analysis","journal":"Cell death & disease","confidence":"Low","confidence_rationale":"Tier 3 / Weak — abstract describes mechanism but provides limited methodological detail for the direct SAMD4B–APOA2 mRNA modification and PD-L1 interaction; single lab","pmids":["38886351"],"is_preprint":false}],"current_model":"SAMD4B is a SAM domain-containing protein that acts as a context-dependent regulator of Wnt/β-catenin signaling and transcription: it suppresses AP-1/p53/p21 transcriptional activity via its SAM domain, stabilizes β-catenin mRNA to activate the Wnt pathway, and is itself regulated by the arginine sensor BAG2—which sequesters SAMD4B when arginine is abundant to promote Wnt-driven growth, and releases it under arginine deficiency to enable β-catenin degradation, ATF4 stabilization, and stress survival."},"narrative":{"mechanistic_narrative":"SAMD4B is a SAM domain-containing RNA-binding protein that acts as a context-dependent regulator of transcription and Wnt/β-catenin signaling in cancer cells [PMID:20510020, PMID:41154652]. Through its SAM domain it suppresses the transcriptional activity of AP-1, p53, and p21 when overexpressed [PMID:20510020]. In breast cancer it operates as a pro-tumorigenic factor: SAMD4B stabilizes β-catenin mRNA, raising β-catenin protein levels and upregulating Wnt/β-catenin target genes (Cyclin D1, c-Myc, Axin2) and TCF/LEF activity to drive proliferation, migration, invasion, EMT, and G1-to-S progression, effects abrogated by Wnt inhibition with XAV-939 [PMID:41154652]. SAMD4B function is gated by the arginine sensor BAG2, which directly binds SAMD4B; under arginine abundance the BAG2–SAMD4B interaction prevents β-catenin degradation and sustains Wnt activity, whereas arginine deficiency releases SAMD4B, leading to β-catenin degradation, ATF4 stabilization, and enhanced stress survival [PMID:40555234]. SAMD4B expression is itself repressed by miR-451 through binding to its 3′-UTR [PMID:34109425].","teleology":[{"year":2010,"claim":"Established the first functional role for SAMD4B as a transcriptional suppressor and localized that activity to its SAM domain, opening the question of which pathways it intersects.","evidence":"Luciferase transcriptional activity assays with overexpression, siRNA knockdown, and deletion mutagenesis in mammalian cells","pmids":["20510020"],"confidence":"Medium","gaps":["No direct DNA or protein target of the SAM domain identified","Mechanism of AP-1/p53/p21 suppression not resolved","Single-lab study without independent replication"]},{"year":2021,"claim":"Identified an upstream regulatory input by showing SAMD4B is a direct miR-451 target, linking its expression to a tumor-suppressive miRNA in colorectal cancer.","evidence":"Dual luciferase 3′-UTR reporter assay, miRNA mimic/inhibitor transfection, overexpression rescue, in vitro proliferation/migration assays and xenograft","pmids":["34109425"],"confidence":"Medium","gaps":["Downstream effectors of SAMD4B in CRC not defined","Does not address SAMD4B molecular mechanism, only its abundance"]},{"year":2024,"claim":"Proposed a catalytic RNA-modifying role for SAMD4B, mediating 2′-O-methylation that destabilizes APOA2 mRNA and thereby modulating PD-L1 and the tumor immune microenvironment in HCC.","evidence":"2′-O-methylation assays, multiplex immunofluorescence, single-cell RNA-seq in PDX models","pmids":["38886351"],"confidence":"Low","gaps":["Limited methodological detail for the direct SAMD4B–APOA2 mRNA modification","Direct catalytic activity not biochemically reconstituted","APOA2–PD-L1 interaction not independently validated"]},{"year":2025,"claim":"Defined SAMD4B as a positive regulator of Wnt/β-catenin signaling that stabilizes β-catenin mRNA, connecting its earlier transcriptional effects to a concrete oncogenic pathway in breast cancer.","evidence":"Overexpression/knockdown functional assays, western blot, TCF/LEF reporter, β-catenin mRNA stability analysis, and XAV-939 pharmacological rescue","pmids":["41154652"],"confidence":"Medium","gaps":["Mechanism by which SAMD4B stabilizes β-catenin mRNA not defined","Reconciliation of mRNA stabilization with prior transcriptional suppression role unresolved","Single-lab study"]},{"year":2025,"claim":"Placed SAMD4B downstream of an arginine-sensing checkpoint, showing BAG2 directly binds SAMD4B to couple amino acid availability to Wnt activity versus stress survival.","evidence":"Unbiased screening in cancer cell lines, direct BAG2–SAMD4B and BAG2–arginine binding assays, BAG2 Q167 mutagenesis, and pathway readouts (β-catenin, ATF4, Wnt activity)","pmids":["40555234"],"confidence":"High","gaps":["Structural basis of the BAG2–SAMD4B interface unknown","How sequestration of SAMD4B controls β-catenin stability mechanistically unresolved","Role of the SAM domain in BAG2 binding not addressed"]},{"year":null,"claim":"It remains unknown how the SAM domain-dependent transcriptional suppression of AP-1/p53/p21 mechanistically integrates with SAMD4B's RNA-binding and β-catenin mRNA-stabilizing activities into a single molecular function.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of SAMD4B","Direct RNA targets beyond β-catenin and APOA2 not catalogued","Native protein and RNA interactome undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[3]}],"localization":[],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,3]}],"complexes":[],"partners":["BAG2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q5PRF9","full_name":"Protein Smaug homolog 2","aliases":["Sterile alpha motif domain-containing protein 4B","SAM domain-containing protein 4B"],"length_aa":694,"mass_kda":75.5,"function":"Has transcriptional repressor activity. Overexpression inhibits the transcriptional activities of AP-1, p53/TP53 and CDKN1A","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q5PRF9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SAMD4B","classification":"Not Classified","n_dependent_lines":301,"n_total_lines":1208,"dependency_fraction":0.24917218543046357},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"INPPL1","stoichiometry":0.2},{"gene":"UPF1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/SAMD4B","total_profiled":1310},"omim":[{"mim_id":"619231","title":"STERILE ALPHA MOTIF DOMAIN-CONTAINING PROTEIN 4B; SAMD4B","url":"https://www.omim.org/entry/619231"},{"mim_id":"610747","title":"STERILE ALPHA MOTIF DOMAIN-CONTAINING PROTEIN 4A; SAMD4A","url":"https://www.omim.org/entry/610747"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Cytosol","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SAMD4B"},"hgnc":{"alias_symbol":["FLJ10211","MGC99832","SMGB","hSmaug2"],"prev_symbol":[]},"alphafold":{"accession":"Q5PRF9","domains":[{"cath_id":"-","chopping":"54-156","consensus_level":"medium","plddt":90.768,"start":54,"end":156},{"cath_id":"1.25.40.170","chopping":"294-398_467-532","consensus_level":"medium","plddt":91.7194,"start":294,"end":532}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5PRF9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q5PRF9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q5PRF9-F1-predicted_aligned_error_v6.png","plddt_mean":64.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SAMD4B","jax_strain_url":"https://www.jax.org/strain/search?query=SAMD4B"},"sequence":{"accession":"Q5PRF9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q5PRF9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q5PRF9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5PRF9"}},"corpus_meta":[{"pmid":"21787333","id":"PMC_21787333","title":"Systematic nomenclature for the PLUNC/PSP/BSP30/SMGB proteins as a subfamily of the BPI fold-containing superfamily.","date":"2011","source":"Biochemical Society transactions","url":"https://pubmed.ncbi.nlm.nih.gov/21787333","citation_count":56,"is_preprint":false},{"pmid":"12887304","id":"PMC_12887304","title":"Psp and Smgb: a model for developmental and functional regulation in the rat major salivary glands.","date":"2003","source":"Biochemical Society transactions","url":"https://pubmed.ncbi.nlm.nih.gov/12887304","citation_count":24,"is_preprint":false},{"pmid":"20510020","id":"PMC_20510020","title":"SAMD4B, a novel SAM-containing protein, inhibits AP-1-, p53- and p21-mediated transcriptional activity.","date":"2010","source":"BMB reports","url":"https://pubmed.ncbi.nlm.nih.gov/20510020","citation_count":16,"is_preprint":false},{"pmid":"10675608","id":"PMC_10675608","title":"Structure and chromosomal localization of the rat salivary Psp and Smgb genes.","date":"2000","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/10675608","citation_count":14,"is_preprint":false},{"pmid":"34109425","id":"PMC_34109425","title":"miR‑451 suppresses the malignant characteristics of colorectal cancer via targeting SAMD4B.","date":"2021","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/34109425","citation_count":12,"is_preprint":false},{"pmid":"11092526","id":"PMC_11092526","title":"Submandibular gland adenocarcinoma of intercalated duct origin in Smgb-Tag mice.","date":"2000","source":"Laboratory investigation; a journal of technical methods and pathology","url":"https://pubmed.ncbi.nlm.nih.gov/11092526","citation_count":12,"is_preprint":false},{"pmid":"15880136","id":"PMC_15880136","title":"Molecular characterization of salivary gland malignancy using the Smgb-Tag transgenic mouse model.","date":"2005","source":"Laboratory investigation; a journal of technical methods and pathology","url":"https://pubmed.ncbi.nlm.nih.gov/15880136","citation_count":10,"is_preprint":false},{"pmid":"40555234","id":"PMC_40555234","title":"BAG2 releases SAMD4B upon sensing of arginine deficiency to promote tumor cell survival.","date":"2025","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/40555234","citation_count":9,"is_preprint":false},{"pmid":"38886351","id":"PMC_38886351","title":"Synergistic immunochemotherapy targeted SAMD4B-APOA2-PD-L1 axis potentiates antitumor immunity in hepatocellular carcinoma.","date":"2024","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/38886351","citation_count":7,"is_preprint":false},{"pmid":"41154652","id":"PMC_41154652","title":"Oncogenic Role of SAMD4B in Breast Cancer Progression by Activating Wnt/β-Catenin Pathway.","date":"2025","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/41154652","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6793,"output_tokens":1431,"usd":0.020922,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8201,"output_tokens":2248,"usd":0.048602,"stage2_stop_reason":"end_turn"},"total_usd":0.069524,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"SAMD4B suppresses transcriptional activity of AP-1, p53, and p21 when overexpressed in mammalian cells; deletion analysis showed the SAM domain is the primary region responsible for transcriptional suppression, and the inhibitory effects could be relieved by siRNA knockdown.\",\n      \"method\": \"Transcriptional activity (luciferase) assays, overexpression and siRNA knockdown in mammalian cells, deletion mutagenesis\",\n      \"journal\": \"BMB reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional assays with deletion mutagenesis and siRNA rescue in a single lab, single study\",\n      \"pmids\": [\"20510020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SAMD4B is a direct target of miR-451; luciferase reporter assay validated miR-451 binding to the 3′-UTR of SAMD4B, and overexpression of miR-451 inhibited CRC cell proliferation and migration partly by suppressing SAMD4B expression.\",\n      \"method\": \"Dual luciferase reporter assay (3′-UTR binding), miRNA mimic/inhibitor transfection, SAMD4B plasmid overexpression, CCK-8/Transwell/flow cytometry, xenograft model\",\n      \"journal\": \"Molecular medicine reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — binding site validated by luciferase reporter plus functional rescue experiments in vitro and in vivo, single lab\",\n      \"pmids\": [\"34109425\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"BAG2 directly binds SAMD4B; when arginine is abundant, BAG2–SAMD4B interaction prevents β-catenin degradation and activates the Wnt/β-catenin pathway. Upon arginine deficiency, BAG2 (acting as an arginine sensor via Q167) releases SAMD4B, leading to β-catenin degradation, ATF4 stabilization, and enhanced cell survival.\",\n      \"method\": \"Unbiased screening in cancer cell lines, direct binding assays (BAG2–arginine interaction at Q167), protein–protein interaction assays (BAG2–SAMD4B), functional pathway readouts (β-catenin levels, ATF4 stability, Wnt pathway activity)\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal methods including direct binding assays, mutagenesis of BAG2 Q167, mechanistic pathway readouts; single lab but rigorous, published in high-tier journal\",\n      \"pmids\": [\"40555234\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SAMD4B promotes breast cancer cell proliferation, migration, invasion, and EMT, and accelerates G1-to-S cell cycle progression by modulating p53 expression; mechanistically, SAMD4B stabilizes β-catenin mRNA, increases β-catenin protein, and upregulates Wnt/β-catenin target genes (Cyclin D1, c-Myc, Axin2, TCF/LEF activity). Inhibition of the pathway with XAV-939 abrogated these effects.\",\n      \"method\": \"SAMD4B overexpression/knockdown functional assays (proliferation, migration, invasion, cell cycle analysis), western blot for β-catenin and downstream targets, TCF/LEF reporter assay, β-catenin mRNA stability analysis, XAV-939 pharmacological inhibition\",\n      \"journal\": \"Biomolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal functional and biochemical methods in a single lab study with pathway inhibitor validation\",\n      \"pmids\": [\"41154652\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SAMD4B mediates 2′-O-methylation modification that destabilizes APOA2 mRNA; decreased APOA2 reduces PD-L1 levels through a direct interaction, thereby modulating the tumor immune microenvironment in HCC.\",\n      \"method\": \"2′-O-methylation modification assays, multiplex immunofluorescence staining, single-cell RNA sequencing in PDX models, mechanistic pathway analysis\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — abstract describes mechanism but provides limited methodological detail for the direct SAMD4B–APOA2 mRNA modification and PD-L1 interaction; single lab\",\n      \"pmids\": [\"38886351\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SAMD4B is a SAM domain-containing protein that acts as a context-dependent regulator of Wnt/β-catenin signaling and transcription: it suppresses AP-1/p53/p21 transcriptional activity via its SAM domain, stabilizes β-catenin mRNA to activate the Wnt pathway, and is itself regulated by the arginine sensor BAG2—which sequesters SAMD4B when arginine is abundant to promote Wnt-driven growth, and releases it under arginine deficiency to enable β-catenin degradation, ATF4 stabilization, and stress survival.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SAMD4B is a SAM domain-containing RNA-binding protein that acts as a context-dependent regulator of transcription and Wnt/\\u03b2-catenin signaling in cancer cells [#0, #3]. Through its SAM domain it suppresses the transcriptional activity of AP-1, p53, and p21 when overexpressed [#0]. In breast cancer it operates as a pro-tumorigenic factor: SAMD4B stabilizes \\u03b2-catenin mRNA, raising \\u03b2-catenin protein levels and upregulating Wnt/\\u03b2-catenin target genes (Cyclin D1, c-Myc, Axin2) and TCF/LEF activity to drive proliferation, migration, invasion, EMT, and G1-to-S progression, effects abrogated by Wnt inhibition with XAV-939 [#3]. SAMD4B function is gated by the arginine sensor BAG2, which directly binds SAMD4B; under arginine abundance the BAG2\\u2013SAMD4B interaction prevents \\u03b2-catenin degradation and sustains Wnt activity, whereas arginine deficiency releases SAMD4B, leading to \\u03b2-catenin degradation, ATF4 stabilization, and enhanced stress survival [#2]. SAMD4B expression is itself repressed by miR-451 through binding to its 3\\u2032-UTR [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Established the first functional role for SAMD4B as a transcriptional suppressor and localized that activity to its SAM domain, opening the question of which pathways it intersects.\",\n      \"evidence\": \"Luciferase transcriptional activity assays with overexpression, siRNA knockdown, and deletion mutagenesis in mammalian cells\",\n      \"pmids\": [\"20510020\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct DNA or protein target of the SAM domain identified\", \"Mechanism of AP-1/p53/p21 suppression not resolved\", \"Single-lab study without independent replication\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified an upstream regulatory input by showing SAMD4B is a direct miR-451 target, linking its expression to a tumor-suppressive miRNA in colorectal cancer.\",\n      \"evidence\": \"Dual luciferase 3\\u2032-UTR reporter assay, miRNA mimic/inhibitor transfection, overexpression rescue, in vitro proliferation/migration assays and xenograft\",\n      \"pmids\": [\"34109425\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream effectors of SAMD4B in CRC not defined\", \"Does not address SAMD4B molecular mechanism, only its abundance\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Proposed a catalytic RNA-modifying role for SAMD4B, mediating 2\\u2032-O-methylation that destabilizes APOA2 mRNA and thereby modulating PD-L1 and the tumor immune microenvironment in HCC.\",\n      \"evidence\": \"2\\u2032-O-methylation assays, multiplex immunofluorescence, single-cell RNA-seq in PDX models\",\n      \"pmids\": [\"38886351\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Limited methodological detail for the direct SAMD4B\\u2013APOA2 mRNA modification\", \"Direct catalytic activity not biochemically reconstituted\", \"APOA2\\u2013PD-L1 interaction not independently validated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined SAMD4B as a positive regulator of Wnt/\\u03b2-catenin signaling that stabilizes \\u03b2-catenin mRNA, connecting its earlier transcriptional effects to a concrete oncogenic pathway in breast cancer.\",\n      \"evidence\": \"Overexpression/knockdown functional assays, western blot, TCF/LEF reporter, \\u03b2-catenin mRNA stability analysis, and XAV-939 pharmacological rescue\",\n      \"pmids\": [\"41154652\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which SAMD4B stabilizes \\u03b2-catenin mRNA not defined\", \"Reconciliation of mRNA stabilization with prior transcriptional suppression role unresolved\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Placed SAMD4B downstream of an arginine-sensing checkpoint, showing BAG2 directly binds SAMD4B to couple amino acid availability to Wnt activity versus stress survival.\",\n      \"evidence\": \"Unbiased screening in cancer cell lines, direct BAG2\\u2013SAMD4B and BAG2\\u2013arginine binding assays, BAG2 Q167 mutagenesis, and pathway readouts (\\u03b2-catenin, ATF4, Wnt activity)\",\n      \"pmids\": [\"40555234\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the BAG2\\u2013SAMD4B interface unknown\", \"How sequestration of SAMD4B controls \\u03b2-catenin stability mechanistically unresolved\", \"Role of the SAM domain in BAG2 binding not addressed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how the SAM domain-dependent transcriptional suppression of AP-1/p53/p21 mechanistically integrates with SAMD4B's RNA-binding and \\u03b2-catenin mRNA-stabilizing activities into a single molecular function.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of SAMD4B\", \"Direct RNA targets beyond \\u03b2-catenin and APOA2 not catalogued\", \"Native protein and RNA interactome undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"BAG2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":5,"faith_pct":80.0}}